VEPP: "Doing Science" in General Education, University Earth Science Courses: Patterns of Seismicity at Plate Boundaries
This is an exercise that is in development and has not yet been fully tested in the classroom. Please check back regularly for updates and changes.
General education courses for non-science majors at many universities are emphasizing active learning methods that attempt to reproduce the process of doing 'real' science, rather than focusing on 'learning' a large body of factual material. Learning outcomes often require a 'research' project in which students define a problem or formulate a hypothesis; find, access and analyze data; and use their analytical reasoning and critical thinking skills to arrive at an independent conclusion.
The distribution of seismicity, heat flow, and magmatism on Earth were the fundamental observations in constructing the plate tectonics paradigm. Essentially, the intent of this project is for students to assemble the relevant data that were used to define plate boundaries and gain insight into plate boundary processes as was done by geophysicists and geologists to prove plate tectonics.
This exercise uses a spreadsheet to organize, plot and analyze data acquired from the IRIS Earthquake browser or the Advanced National Seismic System earthquake catalogs to define, compare, and contrast the geometry of two different subduction zone-volcanic arc systems.
This project is an example of the type of activity that will be required for satisfying learning outcomes associated with a general education (100 level, freshmen non-science major) course in Intellectual Inquiry in the Natural Sciences at the University of Kentucky.The learning outcomes require that students demonstrate the ability to complete a project using scientific methods that includes design (hypothesis formulation, problem statement), data collection (primarily using original databases), data manipulation and analysis (graphical, statistical, quantitative), making inferences and drawing conclusions, and oral and written presentation of their results to peers. The classes in which this exercise will be used have 100 students, a lecturer, two TAs, and a 2:1 lecture:recitation format (25 students/section). Lecture will provide time to present relevant content and review use of relevant software and web pages. The project is intended to be completed in the last 4 weeks of the term, so that
The example presented here uses world-wide earthquake location catalogs to analyze the variation in subduction zone geometry (e.g., angle of subduction) and crustal structure at ocean-ocean and continent-ocean plate boundaries. The question that serves as the basis for this example is: "What are the factors that control the distance from the trench to the volcanic arc in convergent oceanic-continent plate settings?" Two subduction zones are used as the basis for comparison and illustration here (Chile and Tonga-Kermadec). This admittedly simple project is merely a starting point for an introductory class. However, more creative and ambitious students could use the wealth of data available at the VEPP website for their project.
Two earthquake catalogs are recommended, based on ease of use of the interface and ability to output data to a format that can be imported into Excel.
The IRIS Earthquake Browser (http://www.iris.edu/servelet/eventserver/map.do) is a graphical interface that is the simplest to use and most instructional. The user immediately sees the location of their study area, and can select a Google Earth satellite view to show topography and bathymetry. The interface allows the user to define a boxed area on a world map at various scales and zoom levels. The user can also define specific time, depth, and magnitude limits. Visual output is in the form of a map of earthquake epicenters, color-coded by depth (click on thumbnail below to see full screen image). Such graphical output is very instructive in its own right! However, for 'real' data analysis, output is also possible in comma- and space-delimited text format that can be opened in Excel. Such data will need to be "cleaned up" ('text to columns', depths converted to negative numbers for plotting) for manipulation in Excel. A maximum of 5000 points can be downloaded from the IRIS site.
The Advanced National Seismic System (ANSS) has a simple interface that allows the user to input the boundaries of the area of interest, but those boundaries need to be known before hand, i.e., students need to know the bounding latitudes and longitudes beforehand (lat-long and other map principles can be covered in class). The user can also specify limits for earthquake magnitudes, a time window, and a depth limit. Up to 10000 earthquake locations can be downloaded. The ANSS interface looks like this:
Several iterations of sizing the data set will probably be necessary. 5000 (IRIS) or 10000 (ANSS) points are probably not necessary for seeing trends in data!
Click on the thumbnails below to see the distribution of earthquakes as a function of depth in central Chile and the northern Tonga-Kermadec subduction zones:
The Andean arc is 2.81 degrees longitude east of the Peru-Chile trench, and the Kermadec arc is only 1.23 degrees west of the trench (determined from line length function in Google Earth). This should reflect differing angles of subduction.
There are several other on-line sources of information and data relevant to earthquakes and seismic hazards that students could use to place their study in a relevant context:
U.S. Geological Survey Earthquake Hazards Program: http://earthquakes.usgs.gov/
Another earthquake search option is available at the U.S.G.S./National Earthquake Information Center. This site is sort of middle ground between the IRIS graphical interface and the ANSS site. Results of an area search can be output to a map or a comma-delimited text file.
Students need to demonstrate knowledge of core content by appropriate and accurate use of concepts such as plate boundary types, geometries, and kinematics; relation of volcanism and seismicity to plate boundary faults; variations in seismicity with depth; geographic coordinate systems (latitude-longitude).
Higher order thinking skills goals:
Students must formulate a hypothesis or problem to be tested in the broader context of plate tectonics theory. They must develop a relevant test, decide on the appropriate data for constructing the test, locate those data at appropriate on-line data sites, understand the origin of those data and level of prior data processing, evaluate the limitations in the data, and then manipulate the data so they are in the proper format for use. They will need to develop the appropriate level of expertise in data manipulation, graphical analysis, and statistical analysis in standard spreadsheet applications.
Other skills goals:
Students will need to develop appropriate interpersonal skills for working in small groups; be able to effectively and accurately communicate the results of their study in a written report, poster session, and/or oral class presentation. Students will need to demonstrate competency in navigating the internet; develop ability to organize and manage large data sets.
Context for Use
The activity is a small group (2-3 students) project that will involve in-class activities (during lecture and recitation) and communication of results and conclusions to classroom peers.
100/25 undergraduate lecture/recitation course with computers and relevant software applications provided by the university.
Briefly describe the type(s) and level(s) of course
Freshman, non-science major, general education, natural sciences requirement.
Skills and concepts that students must have mastered before beginning the activity
Students should be able to demonstrate knowledge of core content by appropriate and accurate use of concepts such as lithopheric structure and composition; plate boundary types, geometries, and kinematics; relation of seismicity to plate boundary faults; variation in seismicity with depth; geographic coordinate systems (latitude-longitude).
Use of internet to access on-line data sources; use of Microsoft Excel data file setup and formatting, graphical analysis tools, and statistical analysis tools (histogram, curve fitting). These skills can be developed through in-class assignments and homework on other topics during the time leading up to the project.
How/where activity is situated in course
Activity is the sole required project for satisfying learning outcomes in application of scientific method to testing hypotheses with real data. The project will take place during the final four weeks of the semester, should take 1 week of class time for hands-on activities, (to discuss background material, demonstrate use of web sites and applications, consultation among students and instructors), and 3 class periods for group presentations.
Description and Teaching Materials
- Advanced National Seismic System: http://www.ncedc.org/anss/catalog-search.html
- IRIS Earthquake browser: http://www.iris.edu//hq/programs/education_and_outreach
- Volcano Exploration Program: Pu'u 'O'o website: https://vepp.wr.usgs.gov/vepp/
- U.S. Geological Survey Earthquake Hazards Program: http://earthquakes.usgs.gov/
- U.S.G.S..National Earthquake Information Center: http://earthquake.usgs.gov/earthquakes/eqarchives/epic/epic_rect.php
Teaching Notes and Tips
Please describe any helpful examples of this activity, as well as any potential variations on this theme:
The on-line catalogs can be used for illustrating the distribution of seismicity in any terrestrial tectonic setting. Other data that could be incorporated into a group activity are heat flow data, magmatic compositional data, elevation/bathymetry data, tilt data, GPS data, and gas compositional data. A preliminary "jigsaw puzzle" group exercise earlier in the semester might also be an appropriate way for students to become more familiar with the data and issues associated with manipulation and analysis of data. The large amount of earthquake location data that can be accessed at the IRIS and ANSS websites could also be used for statistical analysis of various earthquake scaling relationships, e.g., the frequency-magnitude distribution (Gutenberg-Richter relationship).
What tips might you offer to other educators planning to use this activity?
Students will be given the grading rubric when the project is assigned. The projects will undergo peer review, TA review, and instructor review using the rubric.
References and Resources
Please list any supporting references or URLs for this activity:
Advanced National Seismic System: http://www.ncedc.org/anss/catalog-search.html
IRIS Earthquake browser: http://www.iris.edu//hq/programs/education_and_outreach
Volcano Exploration Program: Pu'u 'O'o website: https://vepp.wr.usgs.gov/vepp/
U.S. Geological Survey Earthquake Hazards Program: http://earthquakes.usgs.gov/
U.S.G.S..National Earthquake Information Center: http://earthquake.usgs.gov/earthquakes/eqarchives/epic/epic_rect.php
U.S.G.S. Volcano Hazards Program: http://volcanoes.usgs.gov/